In the third year of the grant three projects will be pursued. First, chronic recording will be made from various subregions of the brain stem reticular formation and the hippocampus during various stages of behavioral arousal. Secondly, the effects of reticular stimulation on the various fields and circuits of the hippocampus will be measured and related to the reticulosepto-hippocampal circuit. Third, the projections of the reticular formation will be analyzed using the recently developed horseradish peroxidase method for tracing central nervous system connections.